Candor compels a recognition of known prior art.
The general applicable areas of classification of this invention would appear to be Class 52 and Class 160. The following is a recitation in chronological order, without regard to relative pertinency, of references which are concerned with related subject matter.
In 1930 a U.S. Pat. No. 1,746,983 issued to Barr relating to a bifold metal window having a simple means for locking such that they (the bifold doors) could not be opened from the outside. The lock system includes Cremorne bolts having two slide pieces both of which connect to a central handle. When the handle is turned or pulled, a force will be exerted on the slide members and they will respectively recess from their keepers located juxtaposed to the window frame at the upper and lower portions of the same. An automatic locking means centering around a pair of snap bolts is also disclosed. Some 34 years later, a U.S. Pat. No. 3,144,077, issued to Dickinson et al concerning folding doors which control the motion of the doors as they are opened and closed. A moveable guiding track is positioned directly above the bifold doors such that both members of the doors can be opened completely regardless of the position of the wall juxtaposed thereto.
In 1966 U.S. Pat. No. 3,246,684 issued to Rudnick for a hinge structure of the non-pinching type. In this mechanism a relatively narrow elongated rectangular intermediate panel is placed on the connection of the two bifold doors. Piano-type hinges are then attached to this elongated narrow piece and to each of the respective doors. Therefore, as they are opened and closed there is no uncovered aperture along the entire length of the bifold doors to pinch fingers. A pre-assembled, pre-hung door unit is described in Winnan, U.S. Pat. No. 3,314,534. Much care is taken to provide a shippable item secured against inadvertent opening during shipment. Normally, the structure is held in place by removable means such as tape or an adhesive strip to prevent an inadvertent opening of the doors. Bifold doors are aligned by means of the apparatus of Lawrence, Jr. U.S. Pat. No. 3,351,973 wherein identically constructed aligner brackets are situated to mesh perfectly when the doors are in the closed position and thereby insure adequate alignment. The mounting means for the brackets are adjustable to a small degree so that a fine-tune alignment can be accomplished during their securement with the doors.
A prefinished frame with plastic decorator panels is described in Weaver, U.S. Pat. No. 3,440,786, issued in 1969, wherein prefinished stiles and prefinished rails enclose a central panel via a receiving groove juxtaposed to one long inside face. The rails are thinner than the stiles and the stiles are elongated and have flanges flanking the central groove to define the rail and receiving channel on the long inside face of the stile. A bifold door system described in Thun et al, U.S. Pat. No. 3,811,486 (1974) concerns a pair of door panels hinged together with a vertical track-way superimposed thereover so that the bifold doors may be opened by sliding a circular item through or along the track means. The doors are respectively pivoted at a point juxtaposed to the frame. The hinges connecting the bifold doors permit the panels to be opened to substantially face-to-face inner engagement and to bias the panels in a closed position substantially flush with the door frame. A retention means is also used to hold the doors in an open position until a predetermined force is applied, at which time a torsion spring is released, which allows the bifold panels to automatically return to the closed position. A male projection is utilized in conjunct association with a female socket (receiving) member to properly align and retain folding doors in Smith, U.S. Pat. No. 3,907,021 (1975). In this system the male member comprises a unified molding of thermal plastic material, usually of cylindrical shape, having a length substantially equal that of the mounting socket; thus, as the male member is inserted into the female member, alignment must be attained and the bifold doors only can be opened by removing the male member axially from the female socket, which requires at least a slight force.
In 1978 U.S. Pat. No. 4,072,548 issued to Gerson et al for a rectangular wood frame panel door which is subdivided to define two or three smaller central openings. These openings are filled with a reinforced polyurethane panel and a thin plywood panel is laminated to the backside of the door. Thus, a door which is strong and weatherproof is constructed from a solid wood frame and has the feel of a hand-curved hardwood frame. Another insulated molded prefabricated panel is discussed in Clark et al, U.S. Pat. No. 4,223,500 (1980), a thermal gap is filled with insulation material to prevent heat loss or gain from one side of the panel to another. A cam lock is provided wherein a locking level attached to a bracket is pivoted about a horizontal axis with a tool such as an allen wrench to engage a second panel having a locking bolt recessed therein. This provides a continuous set of insulated panels. Another plastic core door is described in Palmer, U.S. Pat. No. 4,265,067 (1981), the disclosure of which encompasses a relatively cogent compendium of decorative panels having foam sandwiched between two sheets of planar material. In this system, the outer skin is comprised of a pleasant looking wood or cellulose material and the core comprises a foamed material having heat insulation capabilities. Finally, in Cowden et al, U.S. Pat. No. 4,272,934 (1981), a panel structure for use in blocking glass panes against the passage of heat and cold is disclosed. These panels, having heat insulation abilities, are held in place by means of a magnet on either side of the window. Thus, the window pane is completely surrounded by sets of insulating material.
Heretofore, the prior art has failed to describe or render attainable an insertable pre-hung bifold door having insulating material throughout, which in the closed position is maintained in such a tight fit that passage of air through any elongated apertures is negligible. This latter quality is derived by a precise tongue-in-groove (tongue and groove) relationship of not only the bifold doors themselves but also the bifold doors with the door frame. In addition, the prior art has failed to take cognizance of a security shutter having opening means only on the inside of the shutter, wherein by the mere turn of a knob or a handle, two elongated rod-like members are withdrawn from apertures within the frame surrounding the bifold doors permitting opening of the same, or in the alternative, when the knob or handle is turned in the opposite direction, the elongated members become inserted into an aperture in the door frame. This prevents either pushing open of the bifold doors from the outside or opening of the bifold doors from the inside without the knob or handle being turned in the proper direction.